1. Field of the Invention
The present invention relates to a method of preparing a Tricholoma matsutake-infected young pine tree by coculturing aseptic seedlings of pine and Tricholoma matsutake. More particularly, the present invention relates to a method of selectively infecting the roots of pine seedlings only with T. matsutake through culturing aseptic seedlings of a pine tree with mycelia of a T. matsutake isolate.
2. Description of the Prior Art
Tricholoma matsutake is a fungus belonging to Basidiomycotina Agaricales Tricholomataceae, and naturally occurs in needle-leaf forests including Pinus densiflora, Pinus pumila, Picea abies and Picea jezoensis. Especially, in Korea, the fungus is known to inhabit only pine forests. The fungus T. matsutake is one of the most-preferred edible mushrooms in Korea and Japan, and is a major source of income especially in the Korean East coast region. The fungus emits a unique fragrance, and aromatic components responsible for such fragrance include 1-octen-3-ol, 2-octanol, 1-octene and 4-methyl cinnamate. The edible fungus T. matsutake, exsisting as a parasite on the roots of live trees, mainly on the fine roots of pine trees (for example, Pinus densiflora), lives symbiotically with the trees while forming ectomycorrhizas. However, there have been no reports of in vitro fruit body formation of the ectomycorrhizal fungus. A Korean research group tried to produce pine trees infected with the fungus T. matsutake in vitro by the conventional method of transplanting pine seedlings into the soil around the fairy rings of the fungus, but the results were not satisfactory (T S Kim, G H Ga, H Park, Y C Park, G H Yoon and G Y Lee. 1999, In vitro cultivation of T. matsutake and increase of its production yield, Publications published by the Korean Forest Research Institute Vol. 153:13-16). The Ibaraki Prefectural Forestry Center reported successful ectomycorrhizal formation of the T. matsutake fungus on seedlings of Pinus densiflora (Akiyoshi Yamada, Ken Maeda and Masatake Ohmasa. 1999. Ectomycorrhizal formation of Tricholoma matsutake isolates on seedling of Pinus densiflora in vitro, Mycoscience 40:455-463).
Because the fungus is a root parasite of live trees, it is difficult to form fruit bodies (mushrooms) of T. matsutake fungus in vitro. For this reason, matsutake mushrooms have been conventionally cultivated simply by controlling environmental factors affecting matsutake mushroom development, such as humidity, light intensity, temperature and the like. That is, favorable environments for matsutake mushroom development were achieved by a series of field work including irrigation, removal of fallen leaves and covering mushrooms with a cup. This cultivation method could significantly increase mushroom yield, but its application was limited to areas where the matsutake mushroom naturally occurs. In more detail, examples of such a mushroom cultivation method include as follows: first, cultured T. matsutake mycelia are spread on the field in which matsutake mushrooms occur, and then newly formed mycelia are transplanted into the soil; second, spores are collected from fruit bodies of T. matsutake and spread on the field in which matsutake mushrooms occur; and third, the live T. matsutake mycelia-containing soil is spread on the field in areas where matsutake mushrooms have not developed. The T. matsutake fungus transplanted by the aforementioned methods failed to grow into fungal colonies owing to its property of having a lower mycelia growth rate than bacteria and other filamentous fungi, resulting in loss of the T. matsutake fungus due to rain or according to soil states while the roots of pine trees are not infected with the fungus.
In addition, matsutake mushrooms can be cultivated by planting seedlings of pine trees into the soil around the fairy rings of T. matsutake, which are naturally formed around pine trees, allowing the seedlings to grow for several years, and then transplanting the resulting pine trees into the matsutake non-mushroom-producing field. However, this method causes the planted pine seedlings to be infected and rooted with a number of other similar fungi that naturally occur in the field, before infection with T. matsutake. Moreover, identification of rooted fungi requires complex experimental techniques. Therefore, pine trees infected with T. matsutake are not obtained in high yield.